I have been looking at Jitsi as a replacement for my current use of Skype, and I ran into the following:

I created two accounts on jit.si to see how things worked. These two accounts (on different computers) connected fine.
However, when I tried to add a contact from a different xmpp server (I used accounts at jabber.org and jabber.no-sense.net), I noticed that the authorization request from both jabber.org and no-sense.net never reached the client on the jit.si server, and neither did the authorization request from the client on the jit.si server.
The authorization requests from jabber and no-sense.net did reach each others clients.

So, my questions are:
- Is the XMPP server at jit.si interconnected with the XMPP network?

All SRV records are properly set. Personally I chat with a number of
non-jit.si accounts every day. Not sure what might have gone wrong in
this case.

- if not: why not?

Not sure, and personally don't have the time to investigate right now.
We'll look at this later if the problem persists.

- Do both parties need to have a jit.si account to use the video bridge on jit.si?